If hamster pups are placed in individual cages at weaning (21 days of age) they begin to hoard food immediately; within 2-6 days, they hoard 90% of the food they take from their food dish in the course of a 1-hr test, consuming only 10% of it. Pups that remain with their littermates after weaning in large group cages do not hoard food until they are placed in individual cages, when hoarding starts immediately. The inhibitory effect of littermates is just as pronounced in hamsters that have been allowed to hoard food in individual cages for 14 days after weaning and are then regrouped into litters. If litters are housed in divided cages that prevent physical interactions among littermates, but allow the interchange of olfactory, auditory, and some visual cues, hoarding is suppressed to an intermediate level. These results show that the presence of siblings inhibits the expression of hoarding, partly as a result of direct physical interactions and partly through the agency of sensory cues. The onset of hoarding following the dispersal of young from the nest cannot be explained as a motivational consequence of the young no longer having access to the mother's food hoard.